Grapevine plant named &#39;Caminante Blanc&#39;

ABSTRACT

A new and distinct variety of grapevine plant named ‘Caminante Blanc’, particularly selected for its high resistance to Pierce&#39;s disease, as well as quality of fruit and wines produced is disclosed.

Botanical classification: Vitis vinifera L.

Varietal denomination: The varietal denomination of the claimed varietyof grapevine plant is ‘Caminante Blanc’.

BACKGROUND OF THE INVENTION

Pierce's disease (PD) is common across the southern United States fromVirginia to northern California. It is also common across Mexico andCentral America. The disease is caused by the bacterium Xylellafastidiosa, which is hosted by a very wide range of native andornamental plants. The bacterium is spread by xylem feeding insects asvectors, primarily sharpshooters. PD is one of the few diseases thatrapidly kills wine, table, and raisin grape cultivars of the cultivatedgrape, Vitis vinifera. Vector populations can be limited withinsecticides, but these are difficult to use near their typicallyriparian native habitat or in the ornamental landscapes in which theyflourish. Breeding for PD resistance has been active for over 70 years,but progress has been very slow due to a poor understanding of thegermplasm and the typically multigenic nature of the resistance in mostof the resistant grape species. The two most commonly grown PD resistantvarieties, ‘Blanc du Bois’ and ‘Lenoir’ (‘Lenoir’ is also known as‘Black Spanish’ or ‘Jacquez’), are F₁ hybrids between V. viniferacultivars and resistant American grape species from the southern UnitedStates, and are therefore only about 50% of V. vinifera. ‘Blanc du Bois’and ‘Lenoir” produce wines with lower quality than V. vinifera winegrape varieties, and they are tolerant of, rather than resistant to, X.fastidiosa infection, which results in their potential to expand areasdamaged by PD due to their ability to act as host plants for thebacteria and vectors.

Grapevine is an important and valuable crop. Accordingly, there is aneed for new varieties of grapevine plant. In particular, there is aneed for improved varieties of grapevine plant that produce high qualityfruit for winemaking and are resistant to Pierce's disease.

SUMMARY OF THE INVENTION

In order to meet these needs, the present invention is directed to animproved variety of grapevine plant. In particular, the inventionrelates to a new and distinct variety of grapevine plant (Vitis viniferaL.), which has been denominated as ‘Caminante Blanc’. Grapevine plantvariety ‘Caminante Blanc’ possesses very strong resistance to thebacterial causal agent of Pierce's disease (PD), and produces very highquality fruit and wines therefrom that are indistinguishable from thewidely grown European wine grape cultivars. Other PD resistant cultivarsare known, but their fruit and winemaking quality are poor in comparisonto ‘Caminante Blanc’ and their resistance is much lower.

In particular, grapevine plant variety ‘Caminante Blanc’ is a white winegrape selection that is about 97% V. vinifera (including 62.5% ‘CabernetSauvignon’, 12.5% ‘Chardonnay’, and 12.5% ‘Carignane’) and is highlyresistant to PD as shown in repeated greenhouse evaluations. Incomparison, the two most commonly grown PD resistant varieties, ‘Blancdu Bois’ and ‘Lenoir’, are only about 50% of V. vinifera. ‘CaminanteBlanc’ has been planted in field trials in Davis and in Ojai, Calif.‘Caminante Blanc’ has small berries and small compact clusters. Itblooms relatively late, ripens mid-season, and has medium productivity.Wines made from fruit of ‘Caminante Blanc’ grown in Davis, Calif. may bedescribed as: ‘light straw-gold color’, ‘apple-melon’, ‘lychee’, ‘floralaromas’, ‘pineapple’, ‘green apple’, ‘juicy’, ‘harmonious’, and‘well-balanced’.

Pedigree and Breeding History

The development of this new grapevine variety is in part a result of thediscovery of a single dominant gene for resistance to Xylellafastidiosa, the bacterial causal agent of Pierce's disease (PD). Thesource of the PD resistance is a form of V. arizonica (‘b43-17’) thatappears to have some V. candicans parentage and is from Monterrey,Mexico. ‘b43-17’ was crossed to the susceptible V. rupestris ‘A. deSerres’ to create the F8909 population, Neither ‘b43-17’ nor ‘A. deSerres’ are patented. The resistance from ‘b43-17’ was found to beinherited as a single dominant gene (locus), and this resistance gene,PdR1, was genetically mapped using the F8909 population by a grapevinebreeding program. Tightly linked simple sequence repeat (SSR) markerswere developed and were used in marker-assisted selection to excludesusceptible plants from evaluation in each round of selection. All theprogeny with PdR1 were tested for PD resistance and only those withstrong resistance were considered for use as parents. Potential parentswere also screened for fruit quality over generations and only thosewith good quality fruit and that appeared like V. vinifera wereselected.

Line ‘F8909-08’ from the F8909 population was crossed to ‘P79-101’, ahighly susceptible, advanced V. vinifera table grape selection from agrape breeding program. The resulting ‘F8909-08’ X ‘P79-101’ F₁generation and progeny thereof were screened with the SSR markers forresistance to X. fastidiosa under greenhouse conditions. A highlyresistant selection from the ‘F8909-08’ X ‘P79-101’ cross, ‘00504-20’,was crossed to another V. vinifera table grape from a grape breedingprogram, ‘B52-89’, to create ‘A81-138’, which was also selected for itsvery high resistance to PD. ‘A81-138’ was then used to cross to V.Vinifera wine grapes for several generations of modified backcrossing toobtain the candidate selection ‘09338-016’, which was later named as‘Caminante Blanc’. These backcrosses were modified because of the highheterozygosity and recessive load found in grapes. Hence, to avoidexposure of deleterious recessive alleles, each generation ofbackcrossing was to a different and unrelated high quality V. viniferacultivar.

Accordingly, the parentage of ‘Caminante Blanc’ is ‘07371-20’ (‘F2-35’(‘Cabernet Sauvignon’ X ‘Carignane’) X ‘U0502-026’ (‘A81-138’ X‘Chardonnay’)) X ‘Cabernet Sauvignon’ to produce ‘09338-016’. ‘CaminanteBlanc’ was particularly selected for its high resistance to Pierce'sdisease, as well as the quality of its fruit and wines producedtherefrom. None of the parents across the multiple backcross generationsare patented. ‘09338-016’ has deeply lobed leaves with large irregularteeth on the leaf margin. ‘Cabernet Sauvignon’ is not only verysusceptible to X. fastidiosa it has deeply lobed leaves, has lobes withsmall sinuses in them and has relatively short teeth on the leaf margin.‘Caminante Blanc’ can be distinguished from its female parent ‘07371-20’in that ‘Caminante Blanc’ has perfect flowers whereas ‘07371-20’ haspistillate flowers.

BRIEF DESCRIPTION OF THE DRAWINGS

This new grapevine plant variety is illustrated by the accompanyingphotographs. The colors shown are as true as can be reasonably obtainedby conventional photographic procedures. The photographs are of plantsthat are five to seven years old. Colors referred to are in reference toThe Royal Horticultural Society Colour Charts Edition V.

FIG. 1 shows simple sequence repeat (SSW) marker data establishing a DNAfingerprint for ‘Caminante Blanc’ with nine pure Vitis viniferacultivars for comparison. Alleles for marker-assisted selection of theXylella fastidiosa locus (PdR1) are shown in red.

FIG. 2 illustrates the upper surface of a leaf of grapevine plantvariety ‘Caminante Blanc’.

FIG. 3 illustrates the lower surface of a leaf of grapevine plantvariety ‘Caminante Blanc’.

FIG. 4 illustrates a section of a shoot tip of grapevine plant variety‘Caminante Blanc’.

FIG. 5 illustrates a plant of grapevine plant variety ‘Caminante Blanc’bearing clusters of berries.

FIG. 6 illustrates a cluster of grapes of grapevine plant variety‘Caminante Blanc’.

DETAILED BOTANICAL DESCRIPTION

The following is a detailed description of the new grapevine plantvariety designated as ‘Caminante Blanc’, including the keydifferentiating characteristics of this variety and comparisons ofcharacteristics of ‘Caminante Blanc’ to other grapevine varieties.Unless otherwise indicated, evaluation data were taken from five- toseven-year-old plants, grown in Davis, Calif.

-   Classification:    -   -   Family.—Vitaceae.        -   Botanical name.—Vitis vinifera L.        -   Common name.—Grapevine.        -   Variety name.—‘Caminante Blanc’.-   Parentage:    -   -   Female parent.—‘07371-20’ (unpatented).        -   Male parent.—‘Cabernet Sauvignon’ (unpatented) Note that            ‘Cabernet Sauvignon’ is a hermaphroditic cultivar and thus            can be used as a maternal or paternal parent.-   Plant:    -   -   Berries.—Small, golden-green, spherical, with thin whitish            bloom.        -   Clusters.—Small to medium, compact, short conical to            cylindrical often winged.        -   Leaves.—Five-lobed, round in outline, over lapping lateral            sinuses, urn-shaped petiolar sinus with naked veins,            distinctive large sharp teeth on leaf margin, lobes have            extra sinus to make them five- to nine-lobed, red-purple            petiole, glabrous leaves.        -   Shoot tips.—Red-bronze, with sparse tomentum.        -   Production.—Blooms relatively late, ripens mid-season,            medium productivity.        -   Method of propagation.—Vegetative propagation via woody or            herbaceous cuttings, or budding and grafting to rootstock.            ‘Caminante Blanc’ has been asexually reproduced in Davis,            Calif. Any rootstock can be used with the variety. Most            often it will be grown on rootstocks that resist grape            phylloxera and or nematodes. In testing, selections were            evaluated grafted on ‘1103P’ rootstock which is not            patented. It was chosen for ease of propagation and because            it is widely used in Calif. The variety has been grafted on            many other rootstocks for testing in field trials as well.

‘Caminante Blanc’ has the highest form of resistance to X. fastidiosacoupled with the highest wine quality of any PD resistant wine grape yetproduced. ‘Caminante Blanc’ is selected for very high resistance, notthe more commonly found tolerance, to prevent the production of hostplants capable of further spreading PD to surrounding vineyards.

‘Caminante Blanc’ has a very strong PD resistance and the highest winequality of any currently used PD resistant wine grape. PD is one of thefew diseases that kill susceptible grapevines. Two most popular PDresistant wine grape varieties, ‘Blanc du Bois’ and ‘Lenoir’ (‘Lenoir’is also known as ‘Black Spanish’ or ‘Jacquez’), were used as controls orstandards in all testing so that the wine quality and resistance of thecandidate variety could be compared to available PD resistant varietiesused across the southern United States. It is noted that ‘Blanc du Bois’and ‘Lenoir’ have relatively poor wine quality and are tolerant, notresistant, to PD. Neither ‘Blanc du Bois’ nor ‘Lenoir’ are patented.

‘Caminante Blanc’ has far better PD resistance and wine quality whencompared with ‘Blanc du Bois’ and ‘Lenoir’. In other words, ‘CaminanteBlanc’ combines very strong resistance to X. fastidiosa with the winequality of internationally acclaimed wine grape cultivars. ‘CaminanteBlanc’ was selected as a variety that exhibits high resistance to X.fastidiosa and V. vinifera-like wine quality. The data presented beloware intended to further characterize ‘Caminante Blanc’. The appearanceof ‘Caminante Blanc’ is illustrated in FIGS. 2-5, and furthercharacteristics of ‘Caminante Blanc’ are shown in FIG. 1 and Tables 1-5.

FIG. 1 presents the DNA fingerprinting profile for ‘Caminante Blanc’ andnine pure Vitis vinifera cultivars for comparison with the standard setof internationally agreed-upon genetic markers. This SSR fingerprintingprofile can be used for DNA-based identification.

Table 1 presents typical phenological data for ‘Caminante Blanc’ grownin the UC Davis vineyards. These data are for 2016, but the ranking ofthe selections in regard to an early cultivar (‘Pinot Noir’) and a latecultivar (‘Cabernet Sauvignon’) have been typical over years. Ingeneral, ‘Caminante Blanc’ is phenologically mid-season. Based upon thepercentage of V. vinifera in the present variety and the data regardingits parents, the variety is expected to grow in USDA Hardiness Zone 6-7.It is not expected to be drought tolerant

TABLE 1 Average phenological states for ‘Caminante Blanc’. ‘CabernetSauvignon’ (late) and ‘Pinot noir’ (early) are included as comparisons.All data were taken from vineyards. 50% 50% Cultivar Budbreak bloomveraison 24 °Brix ‘Caminante Blanc’ 3/17 5/6  7/20  8/17 ‘CabernetSauvignon’ 3/24 5/7  7/21  8/30 ‘Pinot Noir’ 3/10  4/30 7/9 8/9

Table 2 presents the average cluster and berry data for ‘CaminanteBlanc’, and averaged over multiple years.

TABLE 2 Average cluster and berry sizes of ‘Caminante Blanc’ and itscomparison varieties. Data are averages over multiple years. Number Avg.t-test Avg. t-test of Cluster Cluster Berry Berry Genotype Years Wt. (g)Wt. Wt. (g) Wt. Clusters ‘Caminante 5 290 ab 1.2 c Compact Blanc’ ‘Blancdu 6 148 d 1.5 a Well-filled Bois’ ‘Cabernet 6 132 d 1.2 c Loose toSauvignon’ well-filled ‘Chardonnay’ 6 196 cd 1.5 ab Well-filled tocompact ‘Lenoir’ 6 157 d 1.3 bc Loose

Table 3 presents the average yield per vine data taken over 2016 to2018.

TABLE 3 Average production data for ‘Caminante Blanc’ and its comparisonvarieties. Data are averages from three years (2016 to 2018). Avg.Yield/ Std. Dev. Number Genotype Vine (kg) (kg) t-test of Years‘Caminante Blanc’ 7.3 0.9 a 3 ‘Blanc du Bois’ 12.7 1.8 a 3 ‘CabernetSauvignon’ 10.9 1.8 a 3 ‘Chardonnay’ 10.9 3.2 a 3 ‘Lenoir’ 20.0 6.8 b 3

Mean berry juice data were also taken and Table 4 presents this dataover a five-year period between 2014 and 2018. These values areconsistent with cultivars that produce high quality wines.

TABLE 4 Average juice data for ‘Caminante Blanc’ and its comparisonvarieties. Data are averages from five years (2014 to 2018). Avg. Avg.titrat- L- t-test t-test able t-test malic t-test Avg. Avg. Avg. Avg.acidity Avg. acid Avg. Genotype °Brix °Brix pH pH (g/L) TA (g/L) MA‘Caminante 22.2 de 3.55 bc 5.8 cd 1.9 bcd Blanc’ ‘Blanc du 23.5 c 3.58bc 5.2 de 2.3 bcd Bois’ ‘Cabernet 25.8 b 3.74 abc 5.2 de 1.9 bcdSauvignon’ ‘Chardonnay’ 23.3 cd 3.68 bc 5.9 cd 2.4 bc ‘Lenoir’ 21.3 e3.96 a 9.1 a 4.5 a

Xylella fastidiosa susceptibility data are presented in Table 5, whichpresents the levels of X. fastidiosa in relationship to tolerant (‘Blancdu Bois’ and to a lesser extent, ‘Lenoir’) and susceptible (‘Chardonnay’and ‘Cabernet Sauvignon’) cultivars. These are also mean data fromrepeated testing over seasons and greenhouses. Because of the highvariation in greenhouse conditions, at least four standards(bio-controls) were always used: ‘b43-17’, ‘Blanc du Bois’. ‘Lenoir’,and ‘Chardonnay’ (and occasionally other V. vinifera cultivars), whichallows the data to be compared across greenhouses, tests and seasons.None of these varieties are patented. These varieties tend to be veryconsistent in the amounts of bacteria they support as well as theseverity of their disease expression. The cut-off between resistant andsusceptible is usually between 75,000 and 250,000 colony forming unitsper milliliter (cfu/ml).

TABLE 5 Xylella fastidiosa concentrations based on ELISA readings andconverted to colony forming units (cfu/ml). Vitis arizonica ‘b43-17’ isthe source of resistance in the breeding program. Geometric Number MeanLeast Sq. Std. of Times Cultivar cfu/ml t-test Mean Error Tested‘b43-17’ 12423 a 9.4 0.2 11 ‘Caminante Blanc’ 126965 b 11.8 0.4 4 ‘Blancdu Bois’ 859096 c 13.7 0.2 11 ‘Lenoir’ 2421748 d 14.7 0.6 2 ‘Chardonnay’5197228 d 15.5 0.2 11 ‘Cabernet Sauvignon’ 6582993 d 15.7 0.8 1

Table 6 shows phenotype of ‘Caminante Blanc’. The variety has normalhermaphroditic flowers and typical floral development as is found incommercial V. vinifera wine grapes.

‘Caminante Blanc’ Berry size (L, W) 1.3 × 1.4 cm Berry weight, 0.8g/round shape Seed number, 2 length and width typical for V. viniferawine grapes, but not measured Cluster #, L, W, 4.0 × 7.0 cm, shape,short compact compactness, 2 narrow conical, clusters/shoot winged todouble Yield kg 11.5 Pruning weights 1.55 kg Trunk width at 3.0 cm 30 cmTrunk color and Rough shaggy texture bark 178D Woody shoots 0.8 cm/6.6cm diameter above cluster/and internode length Woody shoot First yearbark texture and color adheres but peels in strips in second year 164BActive shoot color, 144C internode color 145A above the cluster 0.8/6.6cm zone/cluster zone shoot diameter/internode length (shoots same sizeas woody canes in the cluster zone) Tendril length, 15.0 diameter 0.2Tendril color, N144D Opposite leaves and alternating 2 nodes skip 2nodes skip Seed color 165B Cluster size L,W 4.0 × 7.0 cm#Berries/cluster 332 Berry color skin 145A and waxy bloom 190D Berryflesh color 145A Leaves L,W 19.0 × 19.0 cm Leaf arrangement, Alternate,shape, and color palmate with 5 Top/Bottom lobes 141A/144B Petiole L,diameter, 10.7 texture 0.4 smooth Petiole color 71A Shoot tip color79A/143A (first opened leaf) Budbreak Mar 17 Bloom date May 12 Harvestdate Aug 18 Peduncle L, diam., 1.0 color, texture 0.5 N144B Smooth

Flower Descriptions

The floral buds and flower clusters are formed with in the latent(dormant) bud in the year before flowering. As the pre-formed nodes onthe compressed stems within the latent bud expand and the flowerclusters begin developing and the individual flowers on the paniclebegin forming. They are very small 2-4 mm and closer to 2 mm with winegrapes.

Berry Descriptions

The variety is not a “slip-skin” type grape. They have skin that adheresto the flesh tightly. They are not firm at ripeness and are softcompared to modern era table grapes at harvest. The pedicels have normalattachment to the berries and are not distinguishable from other V.vinifera wine grapes in this or other morphological features, nor injuice and wine analysis.

Fruit and Juice Parameters

YAN is yeast assimilable nitrogen and helps predict fermentationsuccess. The white grapes have no tannin or anthocyanin values. Seedcolor is rated as green to brown for mature seeds.

Leaf Descriptions

Rounded leaves with lateral lobes with deep sinuses, and sinuses cuttinginto the lateral lobes, lyre-U shaped petiolar sinus, large irregularteeth, light tomentum on the adaxial leaf surface, red (71A) petioleswith color that diffuses into the main veins

Berry Descriptions

The variety is not a “slip-skin” type grape. They have skin that adheresto the flesh tightly. They are not firm at ripeness and are softcompared to modern era table grapes at harvest. The pedicels have normalattachment to the berries and are not distinguishable from other V.vinifera wine grapes in this or other morphological features, nor injuice and wine analysis.

Fruit and Juice Parameters for the 5 Releases

YAN is yeast assimilable nitrogen and helps predict fermentationsuccess. The white grapes have no tannin or anthocyanin values. Seedcolor is rated as green to brown for mature seeds.

Table 7 presents the wine characteristics of ‘Caminante Blanc’

TA L-malic Potassium YAN (mg/L, °Brix (g/L) pH acid (g/L) (mg/L ) as N)‘Caminante 21.3 5.7 3.50 1.3 1660 226 Blanc’

Table 8 presents the juice, fruit and seed phenotype of ‘CaminanteBlanc’

Skin Seed Seed Tannin Color Tannin Juice Juice Juice Skin (1 = low, (1 =gr, Seed (1 = high, Hue Intensity Flavor Flavor 4 = high) 4 = br) Flavor4 = low) ‘Caminante green Lt light green grass, veg, 3 4 spicy, hot, 2Blanc’ apple astringent sl bitter

‘Caminante Blanc’ has excellent PD resistance. However, it is highlysusceptible to a wide range of pests and diseases in a manner similar toother V. vinifera cultivars, and thus it must be treated as a pure V.vinifera cultivar are treated in terms of susceptibility to fungaldiseases and pests. ‘Caminante Blanc’ has no known tolerance to adverseweather.

What is claimed is:
 1. A new and distinct variety of grapevine plantdesignated ‘Caminante Blanc’ as shown and described herein.